Principles of Genetics and Breeding

1.1.5.1 The DNA Era

1944 - Avery O.T., Macleod, C and Mc Carty, M - Transformations of Pneumococcus bacteria by transfer of DNA. DNA is the genetic material.

1950 - Erwin Chargaff shows that the four nucleotides are not present in nucleic acids in stable proportions, but that some general rules appear to hold (e.g., that the amount of adenine, A, tends to be equal to that of thymine, T).

1951 - Barbara Mc Clintok- presence of mobile genetic elements (transposons) in chromosomes of maize that influence gene expression and evolution.

1951 - F. Sanger - sequence of the amino acids of insulin hormone.

1952 - Lederberg - plasmid term for extrachromosomal DNA.

1952 - The Hershey-Chase experiment proves the genetic information of phages (and all other organisms) to be DNA.

1953 - J.D. Watson and F.H.C. Crick –Proposed molecular model for the chemical structure of DNA.

1957 - A. Kornberg - discovered DNA polymerase.

S. Ochoa - discovered RNA polymerase.

1955 - Olivier Smithies developed starch gelelectrophoresis.

1958 - M. Messelson and F.W. Stahl - showed that DNA replication is semi-conservative.

1959 - Swarup – First to induce triploidy in fish-the three-spined stickleback, Gasterosteus aculeatus.

1960 - Hickling – Produced monosex population of Tilapia through hybridization.

1961 - F. Jacob and J. Monod - Lac operon concept- how genes are switched on and off.

1966 - M. Nirenberg and H.G. Khorana - Genetic code deciphered.

1966 - H.G. Khorana - First chemical synthesize of a gene.